Conventionally, a white light-emitting LED is widely used, which is of a double color admixture type of which white light is produced by combining a semiconductor light-emitting element releasing blue light with a yellow light-emitting fluorescent material to mix the blue light and yellow light. However, there is a problem in that the white light emitted by the white light-emitting LED of the double color admixture type is not sufficiently pure. Therefore, recently, there is developed a white light-emitting LED of a triple color admixture type which combines a semiconductor light-emitting element emitting ultraviolet light (wavelength: 350 to 430 nm) with a blue, green, and red light-emitting fluorescent materials to excite the fluorescent materials with light released from the semiconductor light-emitting element, thereby giving white light by mixing blue light, green light, and red light.
Conventionally, green light-emitting fluorescent materials having various compositions have developed. For example, in Patent Literature 1, a fluorescent material equivalent to (Ba,Sr)2SiO4:Eu is described as the green light-emitting fluorescent material used for LEDs or the like. The present literature describes that, at least one of an alkali metal element, an alkali earth metal element, Zn, Y, Al, Sc, P, N, a rare earth element, and a halogen element is contained as a trace element, and the content of the trace element is usually 1 ppm to 100 ppm are described. However, examples in which the trace element is added are not described.
In Patent Literature 2, a green light-emitting silicate fluorescent material containing Eu-activated strontium barium silicate and 0.15 to 0.90 mol of magnesium per 1 mol of the content of silicon is described.